Motorola M68CPU32BUG Manuel d'utilisateur télécharger pdf (Page 32)

APPENDIX 7

A MC68000 assembly language program listing containing assmebler directives to deﬁne

memory constants, a subroutine deﬁnition, and a main program which calls the subrou-

tine.

* Program 1 - Adds two numbers using a subroutine

* makes use of parameter passing using CPU registers

* T. Obuchowicz

* August 29, 2010

* define a subroutine which adds two numbers

* the addend and augend are expected to be in registers D0 and D1

* the sum is returned via register D1

00003000 ORG $3000

00003000 d240 MYSUB ADD D0,D1

00003002 4e75 RTS

* define some memory locations which hold the

* numbers to be added and place to store the

* sum

00004000 ORG $4000

00004000 0001 MICK DC.W 1

00004002 0002 KEITH DC.W 2

00004004 0000 RON DC.W ?

* The main program

00005000 ORG $5000

00005000 3038 4000 MOVE MICK,D0

00005004 3238 4002 MOVE KEITH,D1

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Motorola M68CPU32BUG Manuel d'utilisateur Page 32